There are known methods of increasing well rates that are applied in cases if the rate is much lower than the estimated rate. Vertical and horizontal relief slots are cut into borehole walls, the effective drainage area is fractured, and the bottom-hole area is processed by strata treating reagents like liquids and powders, for example.
The most effective of above-mentioned methods is the discharge of the well area by the cutting of slots and that means the formation of orientable slot-like cavities. Such a method can increase the well rate by several times and maintain it for a long time period. Methods of fracturing and strata treatment provide less effect, which usually does not last long and makes necessary periodical repeated well treatment. Besides that, when the strata is treated by chemical reagents considerable difficulties arise when the strata treating solution is being delivered to the strata—huge amounts are lost when the liquid is injected into the borehole. This process changes the compound and can badly impact injecting devices, constructive elements and the borehole.
Usually well rate increasing methods are combined. For each case, the sequence of methods applied are selected based on the well economic and technical optimal conditions for each of them are selected.
There are also numerous detailed implementations of mentioned methods. Among one of known methods is the construction of horizontal slot key seats located in the well zone above and below of the productive strata (and in the strata itself, if it is thick enough). Such slots are at the expense of formation of dome-shaped mine in the well area “transfer” the abutment zone inside the strata. In fact, the creation of such key seats increases the well radius pro rata the depth of the slot formation at the places of formation of horizontal slots.
The construction of horizontal slots in the well area within the productive strata interval helps ‘clean’ the wall packing zone in the slots interval. In the bearing pressure zone tension meanings are close to rock solidity indexes and the creation of such bearing pressure zones considerably decreases rock characteristics. When a fracture is formed in the horizontal slot well it requires lower indexes of surface pressure and its extension within the strata will exceed the horizontal slot diameter.
The creation of two opposite vertical discharging slot key seats in the well zone, the depth of which will not be less than two well diameters for the all productive strata capacity, orientated straight across main tensions in the strata is more effective. At the edges of such key seat stress concentrators cause the re-distribution of stresses in the well area. Such re-distribution forms a rather powerful (more than the depth of the wall packing zone) high penetration zone (the discharges zone, the length of such zone from the forming capital string often exceeds 20–30 well diameters, and its width is equal to the sum of slot depths at each side plus the well diameter). When the border of the discharge zone initiates a fracture crack during fracturing, such a crack is always formed outside the wall packing zone. This method is hindered by the necessity to orientate discharge slots and to determine the direction of the main compounding stresses in the massive.
There is also a method providing for the creation of two opposite vertical discharging slot key seats in the well zone, the depth of which will not be less than two well diameters for all productive strata capacity, orientated straight across main tensions in the strata. For the purpose of additional slot discharge of the effective drainage area a second pair of vertical slots is formed in the well. They are placed symmetrically to the well, at the same time the second pair of slots is orientated across the first one and is not less than 0.5 depth of main slots.
The optimization of the last method consists in the selection of the width of the key seat opening and of its depth, and the depth of each key seat for main slot key seats (L)—is not less than 2 well diameters (d) from the forming one and the t opening should not be less thant=1,6γH/Ea; a=2L+d;                 where γH—is the ground pressure at the depth of H, E—the coefficient of rock elasticity, a—the summary size of the well and two slots: a=2L+d.        
The optimization of sizes of the second (additional) pair of slots consists in the selection of their depth of no less than 0.5 the depth of the main slots with the same opening. The method provides for the formation of two pairs of slot key seats located symmetrically from the well. Pairs of key seats are located opposite each other.
Though the prior art methods have merit—high efficiency, cost effectiveness, long lasting results, they have several principal shortcomings:                Difficulty and sometimes impossibility in determining the force vectors of main stresses, across which the slots should be formed;        Difficulty and sometimes impossibility to orient the created slot in the well zone to a given direction;        High labor intensity in creation of discharge cavities without optimal guarantees and guarantees to increase the well rate.        
Mentioned shortcomings do not allow increasing well rates up to their potential possible index and/or up to their estimated amount.